This randomized, double blind, placebo controlled, multicentric, clinical study will assess the efficacy and safety of Udenafil (100 mg) tablets in patients suffering from erectile dysfunction(ED).

Inclusion Criteria:

• Male patients of 18 to 60 years of age.
• Patients in a stable, monogamous sexual relationship with a female partner for at least 6 months and willing to maintain this relationship for the duration of the study.
• Patients with established diagnosis of erectile dysfunction (ED) of organic, psychogenic or mixed etiology for at least 6 months duration.
• Patient willing to attempt at least one sexual intercourse in a week for the entire treatment.

Exclusion Criteria:

• Patients with total erectile failure or any other sexual disorder such as hypoactive sexual desire.
• Patients who have previously failed to respond to PDE-5 inhibitors like Sildenafil, Vardenafil or Tadalafil.
• Patients who have used other erectile dysfunction therapies within 14 days (2 weeks) prior to entering into this study (i.e. visit 1).
• Patients with hypogonadism or anatomical deformity of the penis such as severe penile fibrosis or Peyronie's disease or penile trauma.
• Patients with a history of major psychiatric disorder.
• Patients with a history of significant pathological cardiovascular conditions such as: congestive heart failure, life-threatening arrhythmia or ischemic heart disease within the past 6 months.
• Patients with a history of central nervous system disorders such as stroke, transient ischemic attacks or spinal cord injury or a radical prostatectomy or radical pelvic surgery.
• Patients with hypotension (<90/50) or uncontrolled hypertension (>170/100), uncontrolled diabetes, hepatic impairment (SGOT or SGPT levels > 3 x Upper Normal Limit), renal impairment (serum creatinine > 2.5mg/dl), hematological disorders such as bleeding disorders.
• Patients with a history of retinitis pigmentosa, proliferative diabetic retinopathy or non-arteritic anterior ischemic optic neuropathy (NAION).
• Patients with a history of sickle cell disease, multiple myeloma, leukemia or any other disorders that may cause priapism.
• Patients on concomitant treatment with nitrates/nitrites(NO) donor, CYP3A4 inhibitors, CYP3A4 inducers, anticoagulants, androgens, antiandrogens or trazodone.
• Patients with known hypersensitivity to PDE 5 inhibitors like Sildenafil, Vardenafil or Tadalafil.
• Patient with known diagnosis to AIDS or with a positive HIV result at study screening visit.
• Patients with any other serious concurrent illness or malignancy.
• Patients with continuing history of alcohol and / or drug abuse.
• Participation in another clinical trial in the past 30days.